1. Field of the Invention
The present invention relates to an air conditioning apparatus for a vehicle, such as an electric car.
2. Description of Related Art
Known in the prior art is an air conditioning apparatus for a vehicle having an air duct that has a first end for the introduction of outside air or recirculated air from a cabin, and a second end opened to the cabin at various locations. A fan is arranged in the duct for obtaining a forced flow of air discharged into the cabin. A refrigerating circuit is provided that is basically constructed of a compressor, an inside heat exchanger arranged in the duct, a pressure reducer, an outside heat exchanger located outside of the duct, and an accumulator. A switching means is provided for switching between a position where a flow of the refrigerant from the compressor is obtained from the outside heat exchanger acting as a condenser, to the pressure reducer, and to the inner heat exchanger acting as an evaporator for a cooling operation of the air in the duct, and a position where a flow of the refrigerant from the compressor is obtained from the inside heat exchanger acting as a condenser, to the pressure reducer, and to the outside heat exchanger acting as an evaporator for a heating operation of the air in the duct.
In such type of cooling apparatus, there has been a strong need to reduce the consumption of power at the compressor. In particular, in case of an electric car, power consumption at the compressor significantly affects the running distance per recharging battery process. In order to save electric power consumed at the heat exchanger, it is preferable to increase the amount of inner recirculated air introduced into the duct, which effectively reduces the load during a heating operation. However, employment of the inner recirculating mode can increase the percent of carbon dioxide in the cabin generated by the respiration of passengers. Thus, it is necessary that a certain amount of outside air be drawn into the duct for air conditioning the cabin. Thus, it is strongly advisable to have as much recirculated air from the cabin for air conditioning as possible, while the amount of outside air introduced be as small as possible.
However, recirculation of the inner air causes condensation to form on the windshield (hereinafter referred to as fogging or clouding) during a heating operation,. For de-fogging, the introduction of an amount of outside air is necessary, thereby resulting in an increased consumption of electric energy.